Spark-plug.



J. R. AYOTTE.

SPARK' PLUG. APPLICATION FILED SEPI. I7, 1917.

1,287,822. X Patented Dee. 17, 1918.

JOSEPH REN .AYOTTEL 0F CHICAGO, ILLINOIS.

SPARK-PLUG.

Specification of Letters Patent.

Patented Dec. 17, 1918.

'Application led September 17, 1917. Serial No. 191,682.

To all whom t may concern:

Be it known that I, JOSEPH REN AYoT'rE, a subject of the King of Great Britain, residing at Chicago, in the county ofA Cook and State of Illinois, have invented certain new and useful Improvements" in Spark- Plugs, of which the following is a specification.

My invention relates to improvements in spark-plugs for internal combustion engines and more particularly towhat is commonly termed a spark-gap for association with the outer end of the plug.

One of the objects of my invention is to provide a spark-gap which can be readily secured on the outer end' of a spark-plug thereby' becoming a permanent part of the plug to which the terminal of the high-tension cable may be readily connected.

Another object of my invention is to provide a spark-plug with a spark-gap incorporated in the outer end thereof with the terminal' of the spark gap positioned in practically the s ame location as the terminal of an ordinary spark-plug 'would be positioned.

A further object of the invention is to provide a spark-gap which may be readily attached or detached from the outer end of the insulating core of a spark plug,1having windows formed in the side wall thereof through which the operation of the gap may be readily observed.

A still further object of the invention is to provide'a rugged, sturdy device which may be manufactured at low cost and will withstand the punishment and abuse to which automobile accessories of this character are subjected.

Still other and further objects will become readily apparent to those skilled in the art from a consideration of the following description and drawings wherein Figure 1 is a side-elevation of my improved spark plug.

Fig. 2 is a longitudinalv sectional view therethrough.

Fig. 3 is a transverse, horizontal sectional view on the line 3-3 of Fig. 1. Fig. 4 is an end view o f the spark plug. Fig. 5 is a side elevation of the insulating core detached from the other parts of the plug, and, l

.Fig 6 is a perspective view of the'terminal electrode detached from the spark gap.

Spark gaps are now a commercially well known article for use in association with the spark plugs of internal combustion engines and it is unnecessary therefore to discuss thetheory of operation or the advantages incident to their use. My invention lies principally in the structural arrangement of the spark gap together with its means for attachment to the outer end of the insulating core of a outer end a terminal for connection with ahigh tension ignition cable. The gap formed between the outer end of the central electrode and the inner end of the short electrode carried by the hood, provides an air space across which the high tension current must pass in the operation of the apparatus. The condition and functioning of the spark plug as an igniter may be ascertained by observance of the nature of the spark passing between this gap. Openings provided in the side-walls of the hood are protected by a transparent window of glass, isinglass or similar material.

Referring more in detail to the specific embodiment of the invention which I have chosen to illustrate for the purpose of making a full and complete disclosure of the invention, the numeral 10 indicates the outer metallic shell of the spark plug threaded at its lower end ll for screw threaded engagement with the cylinder of a gas engine. The upper end of the shell is of hexagonal shape as at 12 to receive a wrench. A central insulating core 13 of porcelain, or any other suitable insulating material, is provided near its inner end with an annular flange 14, beyond which the diameter of the core is considerably reduced as at 15 to lie within, and may be spaced from, the lower end of the shell 10. The tia-nge portion 14 of the core lies within the enlarged upper end portion of the shell 10 and at its inner end coperates with the shoulder 16 formed within the shell, its upper edge coperating with the inner end of a nut 17 which is in screw threaded engagement with the inner upper end of the shell 10. Packing rings 1'8 and 19 engage the upper and lower edges of thelshulder 14 to allow for uneven expansiorli of the parts and provide a gas tight sea A central opening is provided throughout the length of the core to receive the central` der. The upper end of the central electrode i which is divided into two parts on a dia-v 20 extends a short distance above the end of the core and is threaded as at 24 to receive a nut 25 for clamping the central electrode in its position within the core.

The spark gap proper comprises a dome shaped hood or shell, 26, the lower portion of which is flanged outwardly as at 27 to extend over an annular projection or head 28 formed on the outer end portion. of the core. The interior of the flange 27 is threaded for engagement with the threaded nut 29 metric plane each part having an inwardly extending bead 30|for engagement with the under side of the annular projection 28. Annular rings or washers 31 are positioned at the upper and lower sides of the annular projection 28y to prevent damage to the core when the two, interengaging parts are screwed together with sulflcient pressure to hold the hood in position.

An electrode 32 extends through an opening in the topl of the hood 26 and at its inner end is provided with a button-shaped, annular enlargement 33 of a shape somewhat similar tothe upper end of the dome 26, but of a less diameter at its inner edge so that its inner edge will be spaced somewhat away from the side wall of the dome to receive and position the upper edge of a cylinder of transparent material 34 which may be of glass, isinglassv or similar substances. The side wall of the dome is provided with apertures as at 35 so as t o permit observation of the spark gap through the transparent material 34. A centrally disposed projection 36 extends from the center of the electrode 32 -into' close proxe rality imity with the upper end 24 of the central electrode, but is spaced apart a slight distance to permit an air gap across which the high tension current must pass. The portion of the electrode 32 which passes through the top of the hood is flattened as at 37 for cooperation with the similarly shaped opening in the hood preventing rotation of the electrode with respect to the hood. The upper portion of the electrode 32 is screwthreaded to receive the clamping nut 38 which locks the same in position within the hood and a terminal screw 39 is threaded on its upper end for engagement with the terminal clip of a high tension ignition cable.

Whereas I have illustrated and described but a single embodiment of my invention, it will be apparent to those skilled in the art that many changes and modifications may be made therein without departing from the spirit of the invention or the scope of the appendedclaims.

Having described vmy invention, what I claim is 1. A spark -plug comprising a shell, a core of insulating material having an annular projection formed on its outer end portion, a ycentral electrode extending through the core, a spark-gap-inclosing-hood positioned over the end of the core, its inner end poirtion being flanged to overlie the annular projection on the core, and having threads formed thereon, and a nut formed of a pluof radially separable parts for co-` operation with the threads on the hood to clamp the same on the annular projection.

2. A spark plug comprising a shell; a core of insulating material having an annular projection formed on its outer end portion to provide an outer and inner shoulder;

a spark-gap-inclosing-hood, positioned over4 the end of the core, having an inner threaded part encompassing said projection, and having an internal shoulder overlying said outer shoulder; a nut formed of a plurality of radially separable parts for coperation with said threads in the hood and having -inner shoulders underlying said inner shoulder on the core, to secure the hood to the core.

In testimony whereof I hereunto set my hand.

JOSEPH REN AYOTTE. 

